Design and experiments of coaxial contra-rotating sugarcane base cutter with time-frequency control

Abstract. To investigate the cutting mechanism of support cutting on sugarcane, a laboratory-based cutting platform with speed control needed to be developed. Based on that, a coaxial contra-rotating base cutter was built to carry out sugarcane support cutting in the lab. The cutting platform, which consisted of two discs with cutting blades, were driven by two variable-frequency electric motors respectively. To synchronize two motors‘ speed and achieve the stepless speed regulating for single motor, a time-frequency controller was designed to handle the nonlinearities and acquire stable system with speed changing. To validate the time-frequency controller controlled base cutter, a series of idle running tests and cane cutting tests were implemented using the laboratory-based cutting platform. The result indicated that the cutting speed of two cutting discs could be adjusted steplessly. Additionally, the controller can limit the overshoot less than 1% in step response of speed and avoid drastic fluctuations which guaranteed the speed difference of two cutting discs less than 2.5rpm. The cane quality by support cutting was also compared to free cutting which revealed that the support cutting can reduce the stubble damage rate from 22.67% to 6.67%. The results also showed that this time-frequency controlled cutting platform could be used for subsequently comprehensive research on sugarcane support cutting.